Transcript SB5. Students will evaluate the role of natural

Evolution:
Patterns of
Change over
Time
BIOLOGY STANDARD
SB5. Students will evaluate the role of
natural selection in the development of
the theory of evolution.
• Relate natural selection to changes in
organisms.
EVOLUTION
Evolution is the theory that
organisms change over time, a
process by which modern
organisms have descended
from ancient organisms.
GENETIC VARIATION
• Evolution is caused by genetic
variation.
• Genetic variation comes from
changes in DNA, which can be
caused by:
–Crossing over (occurs during
Prophase I of meiosis I)
–The random assortment of
genes (during meiosis II)
–Mutations (in genes and
chromosomes)
–Artificial selection
–Natural selection
ARTIFICIAL SELECTION
• Artificial selection takes place
with human control or
direction.
• Examples of artificial selection
–Selective breeding
–Genetic engineering
EXAMPLE OF
ARTIFICIAL SELECTION
• Broccoli, cabbage, kale,
cauliflower, and kohlrabi are
common vegetables that were
cultivated from forms of wild
mustard.
• This is evolution through artificial
selection.
NATURAL SELECTION
Natural selection is the process
by which organisms that are
best suited to live in an
environment survive, passing
on their genetic traits to their
offspring.
NATURAL SELECTION
• Natural selection takes place
without human control or
direction.
• Over time, natural selection
results in changes in the
characteristics of the
population.
ACTIVITIES
“Modeling Camouflage and Natural
Selection”
“Modeling Natural Selection”
BEFORE DARWIN:
LAMARCK’S THEORY OF
EVOLUTION
LAMARCK:
USE AND DISUSE
• Any organ that is used more will
grow larger & stronger
• Areas that are used less will
become smaller & weaker
LARMARCK:
INHERITANCE OF ACQUIRED
TRAITS
• Any characteristic an organism
possesses will be passed on to its
offspring.
• For example:
–Giraffes have long necks
because they had to reach the
food in trees this caused their
necks to become larger
according to use and disuse.
–Giraffes with long necks then
passed on these long necks to
their offspring according to
transmission of acquired
characteristics.
Lamarck believed that the long necks of
giraffes evolved as generations of giraffes
reached for ever higher leaves.
CHARLES DARWIN’S
THEORY OF EVOLUTION
DARWIN’S THEORY OF
EVOLUTION
• The theory of evolution was
proposed by Charles Darwin after
observing the plants, animals,
and fossils of the Galapagos
Islands.
• Darwin noticed that species
varied from island to island.
ACTIVITIES
“Graphing Bird Adaptations”
“Comparing Adaptations of Birds”
SUMMARY OF
DARWIN’S THEORY
1. Individual organisms in nature
differ from one another. Some of
this variation is inherited.
2. Organisms in nature produce
more offspring than can survive,
and many of those that survive
do not reproduce.
3. Because more organisms are
produced than can survive,
members of each species must
compete for limited resources.
4. Because each organism is
unique, each has different
advantages and disadvantages
in the struggle for existence.
5. Individuals best suited for their
environment survive and
reproduce most successfully.
The characteristics that make
them best suited to their
environment are passed on to
offspring. Individuals whose
characteristics are not as well
suited to their environment die or
leave fewer offspring.
6. Species change over time. Over
long periods, natural selection
causes changes in the
characteristics of a species,
such as in size and form. New
species arise, and other species
disappear.
7. Species alive today have
descended with modifications
from species that lived in the
past.
8. All organisms on Earth are
united into a single tree of life by
common descent.
TERMS TO KNOW
HOMOLOGOUS
STRUCTURES
structures which have different
mature forms but develop from
the same embryonic tissue
ANALOGOUS STRUCTURES
structures which look and
function similarly but do not
share the same evolutionary
history
Bat wings and bird wings are
analogous as flight structures:
their structure and function have
evolved by different routes from a
flightless reptilian ancestor.
Note that a good portion of the flight
surface in bats consists of a
membrane stretched between the
extended bones, whereas the bones
of the bird are relatively small and
do not support the flight surface.
MICROEVOLUTION
• Evolution that occurs within the
species level
• Microevolution results in the
creation of new species.
• New species evolve as
populations become
reproductively isolated from each
other
EXAMPLES OF REPRODUCTIVE
ISOLATION
• Behavior (behavior isolation)
• Geography (geographic isolation)
• Reproductive timing (temporal
isolation)
SPECIATION
• The development of one or more
species from an existing species.
• Historical example of speciation
–Darwin’s finches
• Current example of speciation
–Diane Dodd’s fruit fly experiment
SPECIATION CONT’D
Diane Dodd’s fruit fly experiment
suggests that isolating populations in
different environments (e.g., with
different food sources) can lead to the
beginning of reproductive isolation.
These results are consistent with the
idea that geographic isolation is an
important step of some speciation
events.
MACROEVOLUTION
large scale evolutionary
changes that take place over
long periods of time; evolution
between different species
Macroevolution
can be
represented by
the
evolutionary
tree.
BIOLOGY STANDARD
SB5. Students will evaluate the role of
natural selection in the development of
the theory of evolution.
• Trace the history of the theory.
• Explain the history of life in terms of
biodiversity, ancestry, and the rates of
evolution.
• Explain how fossil and biochemical
evidence support the theory.
THE HISTORY OF LIFE
FOSSILS
• Fossils are the mineralized
remains of animals or plants or
other artifacts such as footprints.
• The totality of fossils and their
placement in rock formations and
sedimentary layers (strata) is
known as the fossil record.
http://en.wikipedia.org/wiki/Fossil
• The fossil record provides
evidence about the history of life
on Earth. It also shows how
different groups of organisms
have changed over time.
• The fossil record reveals that
fossils occur in a particular order:
some only in older rock and some
only in more recent rock.
• The study of fossils is called
paleontology.
DATING FOSSILS
• Relative dating allows
paleontologists to estimate a
fossil’s age compared with that of
other fossils.
• In radioactive dating, scientists
calculate the age of a sample
based on the amount of
remaining radioactive isotopes it
contains.
• Scientists use the half-life of
radioactive isotopes to date
fossils.
HALF-LIFE
• A half-life is the length of time
required for half the radioactive
atoms in a sample to decay.
• Radioactive isotope with a short
half-life: carbon-14 (5730 years)
–Used to date younger fossils
• Radioactive isotope with a long
half-life: potassium-40 (60,000
years)
–Used to date older fossils
GEOLOGIC TIME SCALE
In the geologic
time scale,
time is divided
the eon, era,
period, and
epoch.
• Remember that macroevolution is
the large scale evolutionary
change that takes place over long
periods of time.
• The events of macroevolution are
reflected in the geologic time
scale.
EVOLUTION OF LIFE
• Early Earth was hot; atmosphere
contained poisonous gases.
• Earth cooled and oceans
condensed.
• Simple organic molecules may
have formed in the oceans.
• Small sequences of RNA may
have formed and replicated.
• First prokaryotes may have
formed when RNA or DNA was
enclosed in microspheres.
• Later prokaryotes were
photosynthetic and produced
oxygen.
• An oxygenated atmosphere
capped by the ozone layer
protected Earth.
• First eukaryotes may have been
communities of prokaryotes.
(endosymbiosis)
• Multicellular eukaryotes evolved.
• Sexual reproduction increased
genetic variability, hastening
evolution.
The Atmosphere of Early Earth
• Earth’s early atmosphere
probably contained hydrogen
cyanide, carbon dioxide, carbon
monoxide, nitrogen, hydrogen
sulfide, and water.
• Thunderstorms predominated.
• Primitive oceans were brown from
dissolved iron deposits.
Could organic molecules have evolved
under the conditions of early Earth?
• In the 1950s, Stanley Miller and
Harold Urey tried to answer this
question.
• A flask was
filled with
hydrogen,
methane,
ammonia, and
water to
represent the
conditions of
early Earth.
• The flask was
sealed to
eliminate the
possibility of
contamination
by
microorganisms
(bacteria,
viruses, and
fungi).
• Electric sparks
were passed
through the
mixture to
simulate the
lightning strikes
of the early
atmosphere.
• Over a few days, several amino
acids (the building blocks for
proteins) began to accumulate.
• Miller and Urey’s experiments
suggested how mixtures of
organic compounds could have
arisen from simpler compounds
present in early Earth.
• Later experiments found that the
Miller/Urey simulation was not
accurate.
• However, similar experiments
based on current knowledge of
Earth’s early atmosphere have
also produced organic
compounds.
BIOLOGY STANDARD
SB5. Students will evaluate the role of
natural selection in the development of
the theory of evolution.
• Explain the history of life in terms of
biodiversity, ancestry, and the rates of
evolution.
• Explain how fossil and biochemical
evidence support the theory.
PATTERNS OF
MACROEVOLUTION
• Five of the six patterns of
macroevolution are
–mass extinctions
–adaptive radiation
–convergent evolution
–punctuated equilibrium
–gradualism
MASS EXTINCTION
• Extinction is the dying out of a
species.
• Mass extinction is the
widespread destruction of a
species caused by many
factors.
ACTIVITY
Reading a Geologic Time Scale
The Mass Extinction of the
Dinosaurs: The AsteroidImpact Hypothesis
Luis and Walter Alvarez
Luis, along with his son Walter, proposed the asteroid-impact
hypothesis.
• At the end of the Cretaceous
period, the dinosaurs, along with
many species of aquatic and
terrestrial organisms, became
extinct.
• In 1980, Luis Alvarez, along with
his son Walter, proposed the
asteroid-impact hypothesis.
• The asteroid-impact hypothesis
suggests that a huge asteroid hit
the Earth, sending so much dust
into the atmosphere.
• This dust blocked the sun, which
caused a change in the Earth’s
climate.
• This change in climate led to the
mass extinction.
• Alvarez and Alvarez noted that
sediments from the end of the
Cretaceous period contained high
concentrations of iridium.
• Iridium is rare in the Earth’s crust,
but it is abundant in asteroids and
other extraterrestrial bodies.
• Quartz crystals, deformed by a
powerful force, were also found in
sediments of this time period.
• Further evidence for this
hypothesis was provided by the
possible site of impact, the
Chicxulub crater located on the
Yucatan Peninsula in southern
Mexico.
• The crater dates from the end of
the Cretaceous period and is (180
km) 110 miles across.
The Chicxulub of the Yucatan
Peninsula
ADAPTIVE RADIATION
• A single species or a small group of
species has evolved into several
different forms that live in different
ways.
• Examples
–Darwin’s finches
–The extinction of dinosaurs cleared
the way for the adaptive radiation of
many species of mammals.
• Figure legend: Adaptive Radiation. New groups come from a
common ancestor. These new groups are suddenly able to exploit
new habitats. If these groups eventually become reproductively
isolated, they may become new species.
CONVERGENT EVOLUTION
The process by
which
unrelated
organisms
come to
resemble each
other.
PUNCTUATED EQUILIBRIUM
• After long stable periods
(equilibrium), new species are
produced by shorter periods of
rapid change.
• Evolution is believed to occur at
different rates for different
organisms at different times.
GRADUALISM
Gradualism is
evolution that
occurs over a long
period of time
when adaptive
changes
accumulate slowly
and steadily over
time in a
population.
Gradualism vs. Punctuated
Equilibrium
Selection
Define:
a. Stabilizing
selection
b. Disruptive
selection
c. Directional
selection
BIOLOGY STANDARD
SB5. Students will evaluate the role of
natural selection in the development of
the theory of evolution.
• Recognize the role of evolution to
biological resistance (pesticide and
antibiotic resistance).
EVOLUTION AND
PESTICIDE
RESISTANCE
Destruction of Natural Enemies
Development of Resistance